摘要
由于目前的CCD尤其科学级CCD的动态范围高达105:1,甚至106:1,此时若要满足ADC的动态范围大于CCD相机的动态范围,则必须选择分辨力为18～20bit的ADC,而航天级或高等级的高分辨力ADC较少且价格昂贵。本文利用CCD相机系统的噪声谱密度跟信号大小有密切关系这一特点,对于强光信号和弱光信号采用不同的信号处理链,从系统通道增益的角度阐述了低分辨力ADC实现高分辨力模数转换的原理及硬件实现方案,最后通过实验室成像测试验证,实验结果表明,用低分辨力A/D转换器采用粗细量化相结合方式实现了高分辨力模数转换,并提高了CCD相机的动态范围。
Contemporary CCD especially the scientific grade CCD dynamic range is up to 100,000 electrons, and even capacity over 100,000 electrons. In order to take full advantage of these characteristics, it is necessary that the dynamic range of Analog-to-Digital Converter （ADC） must exceed the dynamic range of the CCD. The number of bits provided by the ADC must exceed 16 bits, while the high reliability and inexpensive 18-20 bit A/D converter is few. Firstly, we analyze CCD noise, and then the principle to extend the dynamic of the CCD in signal processing chain is presented using two low resolution ADC with different sensitivity. Then, we present a concrete example of improving the resolution of the ADC by two parallel low resolution ADCs. Finally, the laboratory imaging test results show that two low-resolution ADCs are used by combining raw quantization with fine quantization to achieve a high resolution, and improve the dynamic range of CCD camera.
出处
《光电工程》
CAS
CSCD
北大核心
2012年第7期141-145,共5页
Opto-Electronic Engineering
基金
国家自然科学基金资助项目(10978005)
